The invention relates to a device for presorting separated thin postal items, of which the distributing information has been successfully read, to sorting final position areas featuring sequentially arranged sorting final positions of a postal item sorting machine corresponding to the read distribution information and to the assigned sorting final position area, with a number of entries for the postal item streams and a number of exits leading to a sorting final position area in each case, with the entries being connected to the exits by connecting paths in each case.
To increase the throughput of sorting machines for flat postal items, although the transport speed cannot simply be increased and the spacings between the postal items (item gaps) in the stream of postal items cannot be reduced below a minimum spacing, handling the items in parallel offers an obvious solution. In such a case two material entries create two streams of postal items which are fed to two segments of the sorting machine which can each process the throughput of one material entry. A prerequisite for the parallelization is that each postal item of the two item streams can reach each destination address of the two segments of the sorting machine which for transport in one plane can be made possible by an intersection of the two postal item streams for example. In such cases the overall throughput is reduced since a correspondingly large gap must be created in one of the postal item streams if two postal items from the two postal item streams are intended for one segment at the same time. In addition the overall throughput is reduced, because, to avoid a collision in one of the postal item streams, a correspondingly large gap must be created if two postal items were to be located in the intersection area at the same time, which would each have be transported into the “other” segment of the sorting machine connected by the intersection.
To avoid these disadvantages an intersection-free transport of the postal items from one material entry in each case to the segment located beyond the other material entry in two transport planes is proposed.
In addition a connecting path is provided from one material entry to the segment beyond the other material entry which intersects with a connecting path from the other material entry to the segment arranged after the first material entry at an intersection (U.S. Pat. No. 4,615,446).
A sorting device is described in EP 0 613 730 A2 in which a number of connecting paths are possible from a specific entry to a specific exit. The connecting paths are formed by transport units located on turntables, arranged in a hexagonal grid structure, which are aligned in accordance with the entries and exits to be connected. In this case however only connecting paths which do not cross each other are ever active at a specific time, with the topology of the paths also being variable over time. Therefore there is also no merging of a number of path sections to a single path section in which collisions between postal items can occur. Because of the many controlled rotatable transport units required, this apparatus has a high level of mechanical complexity.